This invention relates generally to the field of telephony, and more particularly to an improved modular distributing frame of a type usually installed in a telephone office. Devices of this general type are known in the art, and the invention lies in specific constructional details which permit ease of manufacture, installation and expansion to accommodate additional circuits when required.
Telephone main frames are used to terminate individual subscriber cable pairs at a convenient location for connection to office equipment for switching or other processing. By terminating the subscriber pairs for appearance at a predetermined area, it is possible to provide for the incorporation of protecting devices in series with the cable pairs, and provide for the testing of circuits for various defects. In the early years of telephony, the number of such subscriber pairs was limited, and space limitations generous. With burgeoning demand, the need for compact construction is ever present, and numerous attempts have been made to design equipment which will require minimum space allocation per cable pair. Most frames feature a skeletonized frame adapted to support various types of connector blocks which provide the appearances for the cable pairs, together with accompanying blocks for the termination of conductors leading to inside plant equipment. Shunt jumpers are used to interconnect the two and more or less space utilization is made depending upon the effectiveness of frame geometry. Blocks must be positioned upon the frame with a view toward obtaining adequate accessibility to personnel, both during initial installation and during subsequent servicing operations. This has resulted in a wide variety of connector block configurations, each offering certain advantages. However, maximum space utilization remains with the use of a traditional two-sided frame. The principal disadvantage of this frame is the necessity of wiring protector blocks on one side of the frame to connector blocks on an opposite side of the frame. Another difficulty lies in the complexity of cable connection at the time of initial installation.